Compare Stephen Crane's imagined depiction of Civil War combat to what a historical record actually documents, and evaluate what fiction can capture that a factual account cannot, and what it risks getting wrong.
Crane wrote The Red Badge of Courage roughly thirty years after the Civil War ended, having never served in any war himself, researching mainly through veterans' recollections and magazine collections of officers' battle accounts rather than personal memory. Remarkably, many actual Civil War veterans who read the novel after its 1895 publication praised its psychological accuracy so strongly that some assumed Crane must have been a veteran himself.
A genuine historical record of a battle, an official report, a unit roster, a diary with specific dates and place names, documents very different things than Crane's novel does. The novel never names the specific battle, the commanding general, or even which state Henry's regiment comes from, and it gives almost no strategic overview of the fighting at all -- an actual historical account would treat exactly these facts as essential. Crane trades that kind of factual specificity for interior, psychological truth: what fear, confusion, and shame feel like from inside one soldier's mind, moment by moment, which no official report is designed to capture.
Mastery looks like: They can name specific differences between what Crane's novel includes and what a historical record documents, and can explain what each kind of text is, and is not, well suited to capture.
Common stumbles: Assuming fiction and historical record serve the same purpose and can be judged by the same standard; dismissing the novel's value entirely just because Crane lacked firsthand experience.